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Sharks are a taxon of significant conservation concern and associated public interest. The scientific community largely supports management policies focusing on sustainable fisheries exploitation of sharks, but many concerned members of the public and some environmental advocates believe that sustainable shark fisheries cannot and do not exist and therefore support total bans on all shark fisheries and/or trade in shark products. The belief that sustainable shark fisheries cannot and do not exist persists despite scientific evidence showing that they can and do, and are important to livelihoods. Additionally, many concerned members of the public are only aware of one threat to sharks and are unaware of other threats-or of most available policy solutions. Here we assess whether the popular press plays a role in spreading misinformation and misunderstanding about these issues via the agenda-setting, priming, and cultivation roles of the media, with the goal of better understanding the causes and consequences of public confusion., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

How can we track population trends when monitoring data are sparse? Population declines can go undetected, despite ongoing threats. For example, only one of every 200 harvested species are monitored. This gap leads to uncertainty about the seriousness of declines and hampers effective conservation. Collecting more data is important, but we can also make better use of existing information. Prior knowledge of physiology, life history, and community ecology can be used to inform population models. Additionally, in multispecies models, information can be shared among taxa based on phylogenetic, spatial, or temporal proximity. By exploiting generalities across species that share evolutionary or ecological characteristics within Bayesian hierarchical models, we can fill crucial gaps in the assessment of species' status with unparalleled quantitative rigor., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In an era of accelerated biodiversity loss and limited conservation resources, systematic prioritization of species and places is essential. In terrestrial vertebrates, evolutionary distinctness has been used to identify species and locations that embody the greatest share of evolutionary history. We estimate evolutionary distinctness for a large marine vertebrate radiation on a dated taxon-complete tree for all 1,192 chondrichthyan fishes (sharks, rays and chimaeras) by augmenting a new 610-species molecular phylogeny using taxonomic constraints. Chondrichthyans are by far the most evolutionarily distinct of all major radiations of jawed vertebrates-the average species embodies 26 million years of unique evolutionary history. With this metric, we identify 21 countries with the highest richness, endemism and evolutionary distinctness of threatened species as targets for conservation prioritization. On average, threatened chondrichthyans are more evolutionarily distinct-further motivating improved conservation, fisheries management and trade regulation to avoid significant pruning of the chondrichthyan tree of life.

Fisheries and aquaculture make a crucial contribution to global food security, nutrition and livelihoods. However, the UN Sustainable Development Goals separate marine and terrestrial food production sectors and ecosystems. To sustainably meet increasing global demands for fish, the interlinkages among goals within and across fisheries, aquaculture and agriculture sectors must be recognized and addressed along with their changing nature. Here, we assess and highlight development challenges for fisheries-dependent countries based on analyses of interactions and trade-offs between goals focusing on food, biodiversity and climate change. We demonstrate that some countries are likely to face double jeopardies in both fisheries and agriculture sectors under climate change. The strategies to mitigate these risks will be context-dependent, and will need to directly address the trade-offs among Sustainable Development Goals, such as halting biodiversity loss and reducing poverty. Countries with low adaptive capacity but increasing demand for food require greater support and capacity building to transition towards reconciling trade-offs. Necessary actions are context-dependent and include effective governance, improved management and conservation, maximizing societal and environmental benefits from trade, increased equitability of distribution and innovation in food production, including continued development of low input and low impact aquaculture.

Theory predicts that bottom-heavy biomass pyramids or 'stacks' should predominate in real-world communities if trophic-level increases with body size (mean predator-to-prey mass ratio (PPMR) more than 1). However, recent research suggests that inverted biomass pyramids (IBPs) characterize relatively pristine reef fish communities. Here, we estimated the slope of a kelp forest fish community biomass spectrum from underwater visual surveys. The observed biomass spectrum slope is strongly positive, reflecting an IBP. This is incongruous with theory because this steep positive slope would only be expected if trophic position decreased with increasing body size (consumer-to-resource mass ratio, less than 1). We then used δ(15)N signatures of fish muscle tissue to quantify the relationship between trophic position and body size and instead detected strong evidence for the opposite, with PPMR ≈ 1650 (50% credible interval 280-12 000). The natural history of kelp forest reef fishes suggests that this paradox could arise from energetic subsidies in the form of movement of mobile consumers across habitats, and from seasonally pulsed production inputs at small body sizes. There were four to five times more biomass at large body sizes (1-2 kg) than would be expected in a closed steady-state community providing a measure of the magnitude of subsidies., (© 2016 The Author(s).)

A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean.

Global climate change has the potential to substantially alter the production and community structure of marine fisheries and modify the ongoing impacts of fishing. Fish community composition is already changing in some tropical, temperate and polar ecosystems, where local combinations of warming trends and higher environmental variation anticipate the changes likely to occur more widely over coming decades. Using case studies from the Western Indian Ocean, the North Sea and the Bering Sea, we contextualize the direct and indirect effects of climate change on production and biodiversity and, in turn, on the social and economic aspects of marine fisheries. Climate warming is expected to lead to (i) yield and species losses in tropical reef fisheries, driven primarily by habitat loss; (ii) community turnover in temperate fisheries, owing to the arrival and increasing dominance of warm-water species as well as the reduced dominance and departure of cold-water species; and (iii) increased diversity and yield in Arctic fisheries, arising from invasions of southern species and increased primary production resulting from ice-free summer conditions. How societies deal with such changes will depend largely on their capacity to adapt--to plan and implement effective responses to change--a process heavily influenced by social, economic, political and cultural conditions.

Coral reefs are rich in biodiversity, in large part because their highly complex architecture provides shelter and resources for a wide range of organisms. Recent rapid declines in hard coral cover have occurred across the Caribbean region, but the concomitant consequences for reef architecture have not been quantified on a large scale to date. We provide, to our knowledge, the first region-wide analysis of changes in reef architectural complexity, using nearly 500 surveys across 200 reefs, between 1969 and 2008. The architectural complexity of Caribbean reefs has declined nonlinearly with the near disappearance of the most complex reefs over the last 40 years. The flattening of Caribbean reefs was apparent by the early 1980s, followed by a period of stasis between 1985 and 1998 and then a resumption of the decline in complexity to the present. Rates of loss are similar on shallow (<6 m), mid-water (6-20 m) and deep (>20 m) reefs and are consistent across all five subregions. The temporal pattern of declining architecture coincides with key events in recent Caribbean ecological history: the loss of structurally complex Acropora corals, the mass mortality of the grazing urchin Diadema antillarum and the 1998 El Nino Southern Oscillation-induced worldwide coral bleaching event. The consistently low estimates of current architectural complexity suggest regional-scale degradation and homogenization of reef structure. The widespread loss of architectural complexity is likely to have serious consequences for reef biodiversity, ecosystem functioning and associated environmental services.

We show how theoretical developments in macroecology, life-history theory and food-web ecology can be combined to formulate a simple model for predicting the potential biomass, production, size and trophic structure of consumer communities. The strength of our approach is that it uses remote sensing data to predict properties of consumer communities in environments that are challenging and expensive to sample directly. An application of the model to the marine environment on a global scale, using primary production and temperature estimates from satellite remote sensing as inputs, suggests that the global biomass of marine animals more than 10(-5) g wet weight is 2.62 x 10(9)t (=8.16 gm(-2) ocean) and production is 1.00 x 10(10) tyr-1 (31.15 gm(-2)yr(-1)). Based on the life-history theory, we propose and apply an approximation for distinguishing the relative contributions of different animal groups. Fish biomass and production, for example, are estimated as 8.99 x 10(8)t (2.80 gm(-2)) and 7.91 x 108 t yr(-1) (2.46 gm(2)yr(-1)respectively, and 50% of fish biomass is shown to occur in 17% of the total ocean area (8.22 gm(-2)). The analyses show that emerging ecological theory can be synthesized to set baselines for assessing human and climate impacts on global scales.

We review interactions between extrinsic threats to marine fishes and intrinsic aspects of their biology that determine how populations and species respond to those threats. Information is available on the status of less than 5% of the world's approximately 15500 marine fish species, most of which are of commercial importance. By 2001, based on data from 98 North Atlantic and northeast Pacific populations, marine fishes had declined by a median 65% in breeding biomass from known historic levels; 28 populations had declined by more than 80%. Most of these declines would be sufficient to warrant a status of threatened with extinction under international threat criteria. However, this interpretation is highly controversial, in part because of a perception that marine fishes have a suite of life history characteristics, including high fecundity and large geographical ranges, which might confer greater resilience than that shown by terrestrial vertebrates. We review 15 comparative analyses that have tested for these and other life history correlates of vulnerability in marine fishes. The empirical evidence suggests that large body size and late maturity are the best predictors of vulnerability to fishing, regardless of whether differences among taxa in fishing mortality are controlled; there is no evidence that high fecundity confers increased resilience. The evidence reviewed here is of direct relevance to the diverse criteria used at global and national levels by various bodies to assess threat status of fishes. Simple life history traits can be incorporated directly into quantitative assessment criteria, or used to modify the conclusions of quantitative assessments, or used as preliminary screening criteria for assessment of the approximately 95% of marine fish species whose status has yet to be evaluated either by conservationists or fisheries scientists.